After a long, hot summer of yard work, you might be eager to simply shove lawn mowers, weed trimmers or tillers into the shed or garage for the winter. But as satisfying as that might be, improper storage of outdoor power equipment can set you up for major headaches in the spring. Without proper preparations, power equipment left sitting all winter faces attacks from the elements and from internal chemical reactions that can cause permanent damage. Debris clinging to metal traps moisture and accelerates rust formation; unlubricated cables and pivot points corrode; and inside the engine, gas and oil become pernicious substances that coat the inside of the carburetor with sludge and gum up the fuel system. If you've ever struggled to start your lawn mower in the spring, you've experienced the mildest effects of improper storage. But more serious damage can occur that requires expensive repairs or replacement parts - calling for a trip to the repair shop at one of the busiest times of the year. And the cumulative effects of improper storage can shorten the life span of your expensive power equipment. The solution is to winterize that equipment before putting it away for the season. The winterizing process is a series of simple steps, such as cleaning, engine maintenance and other preparations, that protect against common mechanical problems. The result is a machine that is ready to fire up and run smoothly every spring for years to come. "With proper maintenance you will get a lot more years out of your equipment," says Gary Honea, a small-engine-maintenance educator with the University of Tennessee Agricultural Extension Service. "These engines can last 15 to 20 years or even longer." Fuel preparation is the most important step in the winterizing process. Gasoline is an unstable mixture of compounds that starts to break down after about 30 days inside a tank or gas can. The process, called oxidization, begins when the most volatile compounds in gasoline evaporate, leaving behind heavier materials that form a gum or sludge. These gummy solids can clog fuel lines and other fine parts of the fuel system, and discolor the inside of the carburetor with a coating called varnish. Old gasoline also harbors another threat: The combination of oxygen, gasoline and metals, such as zinc, copper and aluminum, fires up a chemical reaction that can dissolve metal. The finely machined parts of a carburetor or fuel pump actually begin to disintegrate. "The damage is non-reversible," says Dann Roark, manager of service training for Briggs & Stratton. "Fixing it requires anything from a carb rebuild to carb replacement." Newer models of power equipment are even more susceptible to these threats, because engine efficiency standards have resulted in smaller passageways and fuel lines - some as thin as a human hair. These fine openings gum up faster than previous generations of small engines, so owners of new machines have even more incentive to learn the following steps. Winterizing Checklist Winterize your power equipment immediately after your final use of the season. That way, gasoline will not have time to oxidize, and you won't have to work outside when the temperature falls below freezing. Before you perform any work, remember to disconnect the spark plug lead to prevent accidental starts. 1. Clean up. Remove grease, dust, clippings and other debris from the equipment. Cover carburetors and flywheels with a plastic bag (sealed with a rubber band), then rinse and scrub with a degreasing cleaner. You can also use compressed air to blow off debris. Don't forget to clean nooks and crannies, where debris typically collects. A good cleaning isn't just for looks. Grass or other plant matter traps moisture that can cause rust. Also, dust and grass buildup on the metal vents and cooling fins of air-cooled engines will hamper heat dissipation when the engine is running. This is also a good time to sharpen and balance lawn-mower blades. A sharp blade prevents rough cutting that causes the tops of grass to turn brown. You can either bring the blade to a repair shop or sharpen it yourself - but remember to check the blade's balance before re-attaching it. An unbalanced blade will cause excessive vibration that loosens bolts and causes metal parts to fatigue. 2. Change oil. Like automobile engines, small four-stroke engines need regular oil changes. The carbon deposits and acids that form in old oil can cause gumming and engine damage similar to the damage caused by old gasoline. Remember to run the engine for a few minutes to heat the oil and circulate it through the engine. That process mixes together the contaminants that have settled in the crank case and other parts of the engine. "Changing the oil when the engine is cold is like not changing the oil at all," Roark warns. Then, drain the oil while it is still hot and refill the crankcase with the type of oil recommended in your owner's manual. 3. Check air filter. Dust and grit clogging your air filter restrict air flow to the carburetor, which can make the engine run rich. Either replace or clean the filter. 4. Add fuel stabilizer or drain gas tank. Engine repair experts agree that gasoline is murder on your engine during winter storage, but they are divided over the best way to fight it. You can either add fuel stabilizer, which is a gasoline additive that slows the oxidization process and prevents sludge from forming, or drain all the gas from the tank and run the engine dry. Running the engine dry is an easy solution, but critics say this method can cause rubber components like gaskets and hoses to shrink and crack - especially in two-stroke engines that use diaphragm-type carburetors - resulting in fuel leaks. Also, running the engine until it quits does not guarantee that all the fuel is out of the system. Even small quantities of fuel remaining in the engine will oxidize. The alternative is to fill the tank with a mixture of gasoline and a fuel stabilizer, such as Golden Eagle's Sta-Bil, or similar products from STP or Briggs & Stratton. Begin by adding the fuel stabilizer to a fresh can of gas - not old gas, which has already begun to oxidize. Then, fill the engine's tank with the fresh, treated gas and run the engine for a few minutes to distribute the mixture throughout the fuel system. Treated gas will protect your equipment for at least a year, and will fire up quickly and operate normally in the spring. 5. Lubricate cylinder. Remove the spark plug and add a tablespoon of motor oil or fogging oil into the cylinder. Then, pull the cord or turn over the starter a few times to thoroughly coat the pistons, rings and cylinder with oil. 6. Disconnect, clean and charge the battery. You don't want your batteries to freeze over the winter. Remove them and check the electrolyte level, adding distilled water if necessary. Also, make sure the battery is fully charged. A partially charged battery that sits unused will develop a problem called sulfation. This is indicated by the appearance of a crystalline lead-sulfate "crust," which will lead to loss of battery capacity and less efficient charging. Also remove any corrosion from the battery terminals using a wire brush. Rinse the battery surface between the terminals with a baking soda and water solution to neutralize any acid and prevent surface leakage current. Then, store the battery somewhere cool and dry. 7. Tighten and lubricate. Tighten and lubricate all nuts, bolts and pivot points. Also lubricate wheel bearings and metal control cables to prevent corrosion. Look for a lubricant that provides long-term protection, such as LPS 2, which protects for up to a year. While some common lubricants, such as WD-40, are excellent all-purpose products, they can be quite volatile and thus are not suited for this particular purpose. Read labels carefully. 8. Store properly. It is best to store equipment inside a shed, garage or basement, out of the rain and cold weather - but watch out for dirt floors. Moisture from the ground will seep into metal parts of your equipment. To store lawn tractors, John Deere recommends propping the tractor's undercarriage on blocks to take the weight off the tires, and then reducing the air pressure in the tires. That way, your tires may last as long as your engine does, now that you know how to protect it during the winter. n Sean Donahue is a freelance writer based in Portland, Maine.